Portal:Astronomy

Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry to explain their origin and their overall evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond Earth's atmosphere. Cosmology is the branch of astronomy that studies the universe as a whole.

Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Egyptians, Babylonians, Greeks, Indians, Chinese, Maya, and many ancient indigenous peoples of the Americas. In the past, astronomy included disciplines as diverse as astrometry, celestial navigation, observational astronomy, and the making of calendars.

Astronomy is one of the few sciences in which amateurs play an active role. This is especially true for the discovery and observation of transient events. Amateur astronomers have helped with many important discoveries, such as finding new comets. (Full article...)

Andromeda is one of the 48 constellations listed by the 2nd-century Greco-Roman astronomer Ptolemy, and one of the 88 modern constellations. Located in the northern celestial hemisphere, it is named for Andromeda, daughter of Cassiopeia, in the Greek myth, who was chained to a rock to be eaten by the sea monster Cetus. Andromeda is most prominent during autumn evenings in the Northern Hemisphere, along with several other constellations named for characters in the Perseus myth. Because of its northern declination, Andromeda is visible only north of 40° south latitude; for observers farther south, it always lies below the horizon. It is one of the largest constellations, with an area of 722 square degrees. This is over 1,400 times the size of the full moon, 55% of the size of the largest constellation, Hydra, and over 10 times the size of the smallest constellation, Crux.

Its brightest star, Alpheratz (Alpha Andromedae), is a binary star that has also been counted as a part of Pegasus, while Gamma Andromedae (Almach) is a colorful binary and a popular target for amateur astronomers. With a variable brightness similar to Alpheratz, Mirach (Beta Andromedae) is a red giant, its color visible to the naked eye. The constellation's most obvious deep-sky object is the naked-eye Andromeda Galaxy (M31, also called the Great Galaxy of Andromeda), the closest spiral galaxy to the Milky Way and one of the brightest Messier objects. Several fainter galaxies, including M31's companions M110 and M32, as well as the more distant NGC 891, lie within Andromeda. The Blue Snowball Nebula, a planetary nebula, is visible in a telescope as a blue circular object. (Full article...)

• ... that Abell 2142, a galaxy cluster, is one of the most massive objects in the universe?
• ... that a jet from one of the component stars of Z Canis Majoris is over 11 light-years long?
• ... that Messier 58 is one of the brightest galaxies in the Virgo Cluster and is 1 of 4 barred spiral galaxies included in Charles Messier's catalog?
• ... that the asteroid 2014 AA entered Earth's atmosphere on the early morning of January 2, 2014, less than a day after it was discovered?
• ... that ATIC, a balloon-borne detector flying over Antarctica, recently found excess cosmic ray electrons that might provide evidence for dark matter consisting of Kaluza-Klein particles?
• .... that the Sun fuses about 620 million metric tons of hydrogen per seconds due to Gravity?

• ... that the galaxy NGC 1700 has a rotating hot gas disk glowing in X-rays after merging with another galaxy three billion years ago?
• ... that the galaxy CDG-2 is over 99.9% dark matter, one of the highest proportions discovered?
• ... that novelist Hal Clement created the planet Mesklin in 1953 based on the real-world suspected detection of an extrasolar planet?
• ... that 1ES 1927+654, a galaxy in Draco, exhibited such extreme nuclear activity that it challenged conventional models of black-hole environments?
• ... that examples of artificial planets in science fiction include Riverworld, the Well World, and the Death Star?
• ... that in many works of fiction, the asteroid belt is the remnants of a destroyed planet?

The five Moons of Pluto include Pluto's small satellite Hydra. Image is an artist's concept of the surface of Pluto, Hydra (center), Charon (right) and Nix (bright dot on left).

3 March 2026 –

Astronomers announce the discovery 1,900 light-years from Earth of TIC 120362137, the tightest known quadruple star system, using data from NASA's Transiting Exoplanet Survey Satellite. (Space.com)

10 December 2025 – Brazil–China relations

Brazil and China begin constructing a joint laboratory for radio astronomic technology with the Federal University of Campina Grande and the Federal University of Paraíba to support space research as both countries work on the BINGO radio telescope. (Reuters)

• 7 March 2009 – The Kepler space telescope is launched by NASA to discover Earth-like planets orbiting other stars
• 13 March 1781 – William Herschel observes Uranus, which he initially believes to be a comet, eventually leading to Uranus being identified as a planet
• 14 March 1986 – The European robotic spacecraft Giotto becomes the first satellite to observe a comet up close when it flies through and photographs Halley's Comet
• 16 March 1926 – Using a mixture of gasoline and liquid oxygen, Robert H. Goddard launches the first liquid-fueled rocket
• 18 March 2011 – MESSENGER becomes the first spacecraft to orbit around the planet Mercury
• 23 March 1912 – Wernher von Braun, a German-American aerospace engineer and space architect is born